The present invention relates to an apparatus for calculating a pattern dissimilarity between two patterns given in the form of time sequences of feature vectors.
To calculate the pattern dissimilarity between two patterns which are given in the form of time sequences of feature vectors, it is necessary to calculate the distance between the vectors no matter how the two patterns correspond with each other on the time sequences. In general, the distance between one vector and another is calculated as the distance between a point and another point each corresponding to the respective vector in the vector space. When a continuously changing pattern, such as voice, is expressed in the form of a discrete time sequence of vectors, the dissimilarity between the two patterns often tends to be calculated at a greatly erroneous value even though the patterns are nearly identical.
The object of the present invention is to provide an apparatus which is capable of accurately calculating the dissimilarity between patterns.
According to the present invention, there is provided a calculating apparatus for calculating a dissimilarity between a first pattern and a second pattern each given by time sequences of vectors in which the distance calculation is performed by adopting a distance between a line segment connecting two points corresponding to adjacent vectors of the first pattern and a point corresponding to one vector of the second pattern. The calculating apparatus comprises means for calculating a distance between two adjacent vectors in a first time sequence of vectors corresponding to the first pattern in a vector space, means for calculating a distance between each of the two adjacent vectors in the first time sequence and a vector in a second time sequence of vectors corresponding to the second pattern in the vector space, and means for calculating a distance between the line segment connecting two points of vectors corresponding to the first pattern and the point of the vector corresponding to the second pattern, based on the calculated distances.
By the present invention, the calculation error conventionally derived when expressing an original continuous pattern as discrete time sequences for the distance calculation can be minimized.